Michael Shepard, P.E. State Roadway Design Office Quality Assurance & Engineering Support

Michael Shepard, P.E.
State Roadway Design Office
Quality Assurance & Engineering Support
Page 1
 Overview
 Identification
 Crash
Analysis
 Benefit/Cost
 Mitigation
Analysis
Strategies
 Justification
and Documentation
Overview
Page 2
Chapter 23
 Two


approval processes:
Design Exceptions
Design Variations
A documented decision to design a highway
element or a segment of highway to design
criteria that do not meet minimum values or
ranges established for that highway or project.
FHWA Mitigation Strategies for Design Exceptions
July 2007
Page 3
Design Exceptions are required when the proposed
design elements are below both the Department’s
governing criteria and AASHTO’s new construction
criteria for FHWA’s 13 “Controlling” Criteria







Design Speed
Lane Width
Shoulder Width
Bridge Width
Structural Capacity
Vertical Clearance
Grade






Cross Slope
Superelevation
Horizontal Alignment
Vertical Alignment
Stopping Sight Distance
Horizontal Clearance (lateral
offset to obstruction)
Design Variations are required when proposed design
elements are below the Department’s criteria and
where a Design Exception is not required.
Not all inclusive
 Border Width
 Sidewalk
 Bike Lanes
 Hand Rails
 Front Slope
Page 4
 Impacts to the natural environment
 Social or right-of-way impacts
 Preservation of historic or cultural
resources
 Sensitivity to context or accommodating
community values
 Construction or right-of-way costs
1.
Basic Information
2.
Design Exception Process
3.
Clarifies Criteria
4.
Potential Mitigation Strategies
5.
Case Studies
http://safety.fhwa.dot.gov/geometric/pubs/mitigationstrategies/index.htm/
Page 5
1. Shoulder Width
2. Cross Slope
3. Horizontal Clearance
4. Bridge Width
5. Stopping Sight Distance
6. Vertical Alignment
7. Structural Capacity
8%
60%
Withdrawn
32%
Denied
Approved
FDOT: 2008 - 2011
Page 6
8%
Withdrawn
32%
60%
Denied
Approved
FDOT: 2008 - 2011
8%
60%
Withdrawn
32%
Denied
Approved
FDOT: 2008 - 2011
Page 7
Justification/Documentation
Criteria
Evaluation / Analysis
Crash

NOMINAL SAFETY
examined in reference to
compliance with standards,
warrants, guidelines and
sanctioned design procedures
Mitigation
Strategies
Benefit/Cost

SUBSTANTIVE SAFETY
actual or expected crash
frequency and severity for a
highway or roadway segment
or intersection
Source: FHWA Resource Center
Developing Strong Justifications for Design Exceptions
Page 8
Identification
Department (FDOT)

Plans Preparation
Manual (PPM)

Standard Index

Structures Manual
AASHTO



A Policy on Geometric
Design of Highways and
Streets (Greenbook)
A Policy on Design
Standards Interstate
Standards
Roadside Design Guide
Page 9
A Policy on Geometric Design of
Highways and Streets (Greenbook)
A Policy on Design Standards
Interstate System
Roadside Design Guide
 If
it appears that meeting criteria may not be
feasible at a particular location,
alternatives should be:
Developed
Evaluated

•Alternative A
•Alternative B
Compared
•Meets Criteria
Page 10
Crash Analysis
Crash Reports Provide Clues
Page 11
Identify the
location(s)
Gather Data
Analyze
Crashes
District Three: SR 97 Escambia County
Identify the
location(s)
Establishing Limits
 Project
Gather Data
Analyze
Crashes
 MP 0.615 – 20.070
 Bridge
 MP 16.087 – 16.101
Page 12
Identify the
location(s)
 Analysis
Period
 5 Complete Years
Gather Data
Analyze
Crashes
Identify the
location(s)
Gather Data
Analyze
Crashes
 What
Years?
 2005 – 2009
 2006 - 2010
 2007 – 2011
 Crash
Analysis Reporting (C.A.R.)
System
 Detail or Summary Reports
 Law Enforcement Crash Reports
(Long Forms)
Page 13
Detail Output
Determine your Project & Design Exception Limits
Page 14
Caution should be used with eliminating crash reports to review!
Caution should be used with eliminating crash reports to review!
Page 15
Identify the
location(s)
Gather Data
Analyze
Crashes
 Crash
Analysis Reporting (C.A.R.)
System
 Detail or Summary Reports
 Law Enforcement Crash Reports
(Long Forms)
Page 16
ONLY the Crash Reports Tells the Story
Page 17
Identify the
location(s)
 Contributing
Factors
 Human (Driver behavior)
Gather Data
Analyze
Crashes
Identify the
location(s)
Gather Data
 Road Condition (Road design)
 Vehicle (Vehicle design and
maintenance)
 Environmental (Weather)
 Crash
Patterns
 Identify Crash Patterns and
Significant Trends.
Analyze
Crashes
Page 18
A Design Exception Request for Substandard
(flat) Cross Slope on a RRR Project:
 5 years of crash data reveals 434 crashes within
the design exception limits.
 61 occurred under wet pavement conditions.
 Further evaluation of the police reports indicate
8 out of 61 crashes which occurred under wet
pavement conditions may have been attributed to
substandard cross slope.
 A crash diagram was used for further evaluation.
Crash Numbers: 4, 5 & 11
Page 19
Benefit/Cost Analysis
 The
Analysis Should Only Include the Benefits
and Costs Attributed Solely
to Each Alternative:
Developed
•Alternative A

•Alternative B
Evaluated
Compared
•Meets Criteria
Page 20
Note: If There Isn’t a Crash History, a B/C Analysis
May Not Be Necessary
Step 1
Years of Crash Data
Step 2
No. of Correctable Crashes
Step 3
Cost Per Crash
Step 4
1. Minimum of 5 most
recent years of crash
data.
Crash Reduction Factor
Step 5
Calculate Benefit
Step 6
Calculate Cost
Step 7
Calculate B/C
Page 21
Step 1
Years of Crash Data
Step 2
No. of Correctable Crashes
2. Number of correctable
crashes that were
directly related to the
deficient roadway
element.
Step 3
Cost Per Crash
Step 4
Crash Reduction Factor
Step 5
Calculate Benefit
Step 6
Calculate Cost
Step 7
Calculate B/C
Step 1
Years of Crash Data
3. Societal Cost provided by
the SSO found in the PPM
by facility type
Step 2
No. of Correctable Crashes
Step 3
Cost Per Crash
Step 4
Facility
Type
HSIPG Cost/Crash by Facility Type
Divided
Undivided
Urban Suburban Rural Urban Suburban Rural
Crash Reduction Factor
2-3 Lanes
Step 5
Calculate Benefit
4-5 Lanes
Step 6
6+ Lanes
Calculate Cost
Interstate
Step 7
Calculate B/C
Turnpike
$260,53 $92,84
$402,00
$228,613
1
7
3
$366,42 $83,35
$83,359 $181,265
$193,774 $94,171
2
9
$107,65
$478,26
$130,385
n/a
n/a
n/a
8
3
$141,19
$295,81
n/a
n/a
n/a
n/a
7
0
$124,45
$215,50
n/a
n/a
n/a
n/a
9
7
$85,851 $151,015
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Step 1
Years of Crash Data
Step 2
No. of Correctable Crashes
4. Found In Order of Preference

Step 3
Cost Per Crash


State Safety Office
FHWA CMF Clearinghouse
FHWA Desktop Reference
Step 4
Crash Reduction Factor
Step 5
Calculate Benefit
Step 6
Calculate Cost
Step 7
Calculate B/C
Step 1
Years of Crash Data
Step 2
No. of Correctable Crashes
Step 3
Cost Per Crash
Step 4
5. The Benefit is the
anticipated total annual
crash cost saving.
Crash Reduction Factor
Step 5
Calculate Benefit
Annual Benefit = No. Correctable Crashes X Cost per Crash X CRF
No. Years of Crash Data
Step 6
Calculate Cost
Step 7
Calculate B/C
Page 23
Step 1
Years of Crash Data
Step 2
No. of Correctable Crashes
Step 3
Cost Per Crash
Step 4
Crash Reduction Factor
Step 5
6.
Cost from the Long
Range Estimate (LRE)
Capital Recovery Factor
Service Life
Discount Rate (4%)
Calculate Benefit
Step 6
Calculate Cost
Annual Cost =  Construction Cost per Feature X (Capital Recovery Factor)
Step 7
Calculate B/C
Step 1
Years of Crash Data
Step 2
No. of Correctable Crashes
Step 3
Cost Per Crash
Step 4
7. The B/C is the Annual
Benefit divided by the
Annual Cost
Crash Reduction Factor
Step 5
Calculate Benefit
Step 6
Calculate Cost
Step 7
Calculate B/C
B = Annual Benefit
C
Annual Cost
Page 24
Mitigation Strategies
In many cases some form
of mitigation can be
accomplished to lessen
any adverse impacts that
may result from the lower
design criteria.
Mitigation Strategies for
Design Exceptions (July
2007) is a resource for
evaluating and
implementing.
Page 25
Mitigation Strategies

Include a Section In Your Report that
Discusses all Mitigation Strategies:
 Existing
 Considered
 Proposed
Page 26
Justification and
Documentation

A Strong Case for an Exception Can Be
Made If:
 The Required Criteria Are Not Applicable to the Site
Specific Conditions.
 The Project Can be as Safe by Not Following the
Criteria
 The Environmental or Community Needs Prohibit
Meeting Criteria
Page 27
A Case Should Not Be Made Based Solely On the

Basis That:
 The Department can save money.
 The Department can save time.
 The proposed design is similar to other designs.

Plans Preparation Manual
Chapter 23

Don’t Forget to Include
the Applicable “A”-“Y”
Requirements in the PPM.
Page 28
 Use Engineering Judgment
 Length of Documentation is Not Important.
 The Key is to Provide Clarity and Completeness To
Someone Not Familiar With the Project or the Design.
Note: Provide Enough Time for Central Office and for FHWA Review
Benefit-Cost
Analysis
Crash
Analysis
Exception/Variation
Identification
Mitigation
Strategies
Justification &
Documentation
Page 29
Exceptions and Variations
Michael Shepard, P.E.
State Quality Assurance Engineer
(850) 414-4330
[email protected]
Quality Assurance Website
http://www.dot.state.fl.us/rddesign/QA/QA.shtm
Mary Lou Godfrey, P.E.
Quality Assurance Engineer
(850) 414-4327
[email protected]
Jeremy Fletcher, P.E., P.S.M.
Quality Assurance Engineer
(850) 414-4320
[email protected]
Patty Vickers
Quality Assurance Support
(850) 414-4346
[email protected]
Page 30